This invention relates generally to electronics and more particularly to variable limit controlled amplifiers for use in precision instrumentation.
The use of limiters on amplifiers in precision instrumentation has been implemented to preclude a signal output from the controlled amplifier from exceeding desired limits in particular circumstances. These limits are typically designed into the circuit in such a way that the output is rigidly bracketed or limited between two hard parameters. A problem exists in this implementation particularly in avionics equipment wherein the amplifier for a servo system must have a limited output to preclude harsh and erratic control surface movement of the aircraft, and yet be capable of much broader output range over the full flight envelope. Furthermore, the typical configuration of having the computer implementation for this feature to control both gain and limits causes some concern relative to detectable failure modes if the single computer should fail. This situation would reduce the reliability for the limit control aspect.